The present invention relates to a blood access device and its method of implantation.
There are a number of situations in which it is necessary to provide for fluid communication with the vascular system. For example, patients suffering from kidney failure require the dialysis of their blood by means external from the body. Blood containing toxic substances, such as urea, uric acid, creatine, phosphorus and calcium, must be removed from the blood system, treated and then returned to the patient. Patients requiring such blood dialysis need treatment at least two or three times per week. Patients suffering from hypoalimentation require a device for providing access to the body's vascular system on at least a daily basis.
One prior method of providing fluid communication with the vascular system involved the insertion of a needle into an artery from which blood to be treated was taken, and the insertion of a needle into a patient's vein for blood return. Such a method proved unsatisfactory due to the difficulty in providing for the healing of the artery upon removal of the needle and the trauma produced by the repeated needle insertions. Such short-comings led to the development of external, and later, internal shunts.
An external shunt involves the insertion of tubes, such as those made of Teflon, into an artery and an adjacent vein in a limb and providing an external communication or shunt between the tubes, which extends from the body of the patient. The shunt between the tubes is required in order to provide flow through the tubes during that period of time that access is not required for blood treatment. Were such circulating blood flow not provided, a blood clot or thrombus could form, as would be the case if the tubes were simply capped creating a static blood volume when the tubes were not in use. Dialysis, for example, is accomplished by connecting the arterial and venous tubing to a suitable dialysis unit. Such an external shunt configuration traumatizes the skin adjacent the Teflon tubes and a path is provided through the skin for infection to enter the patient's body. Furthermore, even with external shunts, blood clots sometimes form within the tubes and create a health hazard to the patient.
The disadvantages of external shunts led to the development of the internal shunt. An internal shunt is performed by joining, within a body, openings between an artery and an adjacent vein. The pressure in the artery being substantially greater than that in the vein causes the vein to become distended, forming a fistula. One or two needles are then inserted into the fistula in order to achieve communication with the patient's vascular system. The patient suffers major discomfort and pain each time the needles are inserted into the fistula. Moreover, the continuous insertions into the fistula cause it to become layered with scar tissue which ultimately prevents further intrusion, thus requiring the formation of another shunt.
Both the internal and external shunts increase the loading on the patient's heart due to the joining of the artery to a vein having a lower pressure, thereby lowering the artery's pressure, and requiring the heart to attempt to regain the original arterial blood pressure. Further, in many cases, the reduced circulation in the distal portion of the limb wherein the shunt is effected impairs the adequate removal of waste products from the muscles and other tissues resulting in weakness of the limb.
An object of the present invention is to provide an atraumatic valve for a blood access device. Other objects and advantages of this invention will become apparent upon a reading of the entire specification, including the drawings and claims.